Despite my lifelong admiration of the female breast, I can honestly say that this never occurred to me:
Other Japanese men engage in the all-too-common handshake scam, where a friendly man pretends to want to shake your hand Western-style, then fondles your breast at the same time.
This comes from the “Women Travellers” section of the Lonely Planet Japan guidebook. Their stuff is generally reliable, as long as you ignore their fondness for treating alternatives to Western medicine and logic as simple fact, and it’s no secret that groping is a significant problem in Japan, so this is probably an accurate and necessary warning.
By the way, their World Food Japan book is excellent. I have a slight preference for What’s What in Japanese Restaurants, but more for the presentation than for the content; more kanji, and they don’t keep using the phrase “traditional restaurant-cum-bar” to describe izakaya (their other Japan books just call them pubs, like everyone else does).
WWiJR is also slightly harder to lose than WFJ; I know I’ve got a copy of it around here somewhere, but it must be hidden under a CD or DVD. I had to use Amazon’s search-inside feature to look up its euphemism for pub. Which, by the way, appears to be censored on some pages, or else their scanning/viewing software has an odd glitch that accidentally deletes the “-cum-bar” part about half the time without affecting anything else on the page.
[and now I dread the search-engine referrals I’m going to get for having those two words in close proximity…]